Myths and Facts: Childhood Vaccines (2026)

FOR DECADES, childhood vaccines have been one of the greatest achievements in public health, dramatically reducing the burden of once-common diseases such as polio, measles, diphtheria and meningitis. Indeed, routine immunizations have saved millions of lives and prevented countless hospitalizations and long-term disabilities. Their efficacy and safety are built on decades of rigorous scientific research, extensive clinical testing and continuous safety monitoring. 

Over the years, several organizations joined forces to develop a single vaccine schedule for children. It all began in 1964 when the American Academy of Pediatrics (AAP), the government and other organizations agreed a unified policy would be the best for U.S. children to save even more lives. These groups formed an independent group of experts known as the Advisory Committee on Immunization Practices (ACIP) in charge of reviewing the latest research and advising the American public on immunizations for children and adults. This resulted in the creation of a single vaccine schedule in 1955. Today, this recommended schedule has vaccines against more than 20 different diseases.¹

According to the National Conference of State Legislatures (NCSL), all 50 states now have legislation requiring specified vaccines for students, and all 50 states, as well as Washington, D.C., are required to follow the vaccine schedule set forth by the Centers for Disease Control and Prevention (CDC). Yet, many states provide exemptions from childhood vaccines, which vary from state to state. For instance, all school immunization laws grant exemptions to children for medical reasons.² Only four states do not allow any type of non-medical exemption.³ And, 44 states and Washington, D.C., grant exemptions for people who have religious objections to immunizations.² 

Despite the overwhelming body of evidence of the safety of vaccines, the childhood vaccination schedule has become increasingly politicized in recent years. And, on March 26 of this year, CDC released a report that stated U.S. child vaccination coverage by age 2 was declining. The report also found that coverage varied by race and ethnicity, poverty status, urbanicity and jurisdiction.⁴ What’s more, according to a news report from the University of Michigan’s Center for Infectious Disease Research and Policy (CIDRAP), “a new Axios/Ipsos American Health Index poll shows Americans are losing confidence in the federal government to make recommendations about childhood vaccines. From June 2025 to March 2026, public trust in federal childhood vaccine recommendations dropped 11 points, from 71 percent to 60 percent, with only eight percent of those polled saying they trust CDC more than AAP.” The report goes on to say, one in three respondents (35 percent) have more confidence in guidelines from AAP than in those from CDC. And, about one-quarter (23 percent) express equal confidence in both sources, while 16 percent are not confident in either source.⁵

Unfortunately, public debate, misinformation and declining trust in health institutions have led some parents to question vaccines’ safety, effectiveness and necessity — despite having protected generations of children. Therefore, understanding the science behind childhood immunization — and separating evidence from misconception — has never been more important for protecting the health of children and communities alike. 

Separating Myth from Fact

Myth: Children don’t need to be vaccinated because infection rates are already so low in the U.S.

Fact: Yes, the rates of infection are low. But, this is due to herd immunity, which occurs when a large portion of a community is immunized against a contagious disease, reducing the chance of a disease outbreak. As long as a large majority of people are immunized in any population, even the unimmunized minority will be protected. For instance, infants, pregnant women and immunocompromised people cannot receive vaccines, so they depend on herd immunity.^6,7

If too many people decide not to vaccinate themselves or their children, this opens up opportunities for viruses and bacteria to establish themselves and spread.⁷ We saw this happen most recently with measles. From January 2025 through early March 2026, there were 3,564 confirmed cases of measles in 46 states, mostly among children and teenagers due to declining vaccination rates. This is the largest number of cases in an outbreak since 2000, when the disease was declared eliminated in the U.S.⁸ While another contributing cause of the measles outbreak is international travel, CDC emphasizes that the majority of cases are among people who were not vaccinated against measles.⁹

Myth: Babies don’t need the hepatitis B (HBV) vaccine if they aren’t at high risk.

Fact: If the HBV vaccine is given only to people who believe they are high-risk, many cases will be missed because it can take decades from the time a person contracts HBV before symptoms become apparent. For instance, even if a parent has had only one partner for over a decade, it’s still possible the parent has the hepatitis B virus since the majority of people with HBV globally are unaware they have it.

HBV is very stable in the environment, capable of remaining infectious for weeks and even months on surfaces, and it requires only a very tiny dose to cause infections. The most common cause of chronic HBV infection is mother-to-baby transmission at birth, which can lead to liver cancer, liver failure and death. Ninety-five percent of babies who contract hepatitis B disease near birth develop the chronic form. The safest bet: getting the HBV vaccine, which induces protective immune responses in 80 to 100 percent of people.¹⁰

Myth: Children receive too many vaccines, too soon, which can weaken their immune systems.

Fact: While many parents worry the number of vaccines administered will weaken their child’s immune system, that’s not true. Infant immune systems are very strong due to the number of antibodies present in their blood, which theoretically would give babies the ability to respond to approximately 10,000 vaccines at one time. If all scheduled vaccines were administered at once, it would only use up slightly more than 0.1 percent of a baby’s immune capacity. Also, the immune system could never truly be overwhelmed because its cells are constantly being replenished. Compared to the countless bacteria and viruses babies are exposed to every day, immunizations are negligible.

Importantly, while babies are administered more vaccines than ever before, small children are actually exposed to fewer immunologic components overall than children in past decades due to the efficiency of today’s vaccines.⁷

Myth: It’s better to acquire natural immunity to a disease than to get vaccinated.

Fact: The benefits of vaccines far outweigh natural immunity simply due to the complications that are likely to arise from infections. According to the Yale School of Public Health, the complications from 10,000 children getting measles infections include 2,000 hospitalizations, 10 cases of brain swelling, 10 to 30 child deaths, 1,000 ear infections with potential permanent hearing loss and 500 cases of pneumonia. On the other hand, complications from 10,000 children getting the MMR vaccine include three fever-related seizures, between zero and one cases of abnormal blood clotting and 0.035 allergic reactions.10 Even chickenpox or the flu can lead to pneumonia, brain inflammation and death.¹¹

Myth: Vaccines contain harmful ingredients.

Fact: Any substance can be harmful in significantly high doses. But, vaccines contain ingredients at a dose that is even lower than the dose all individuals are naturally exposed to in the environment. 

Most of the concern about the ingredients in vaccines centered on thimerosal, mercury, formaldehyde and aluminum. 

Thimerosal, which is a mercury-containing compound, is a preservative that was removed from childhood vaccines in the U.S. starting in 1999 as a precautionary measure. However, it was used recently in multidose vials of influenza vaccines, but the influenza vials containing thimerosal were discontinued as of 2025. Today, there are no U.S. vaccines that contain thimerosal or mercury.⁶

Formaldehyde is present in some vaccines as an inactivating agent and is also used to detoxify bacterial toxins in some vaccines. However, it is also found in carpets, upholstery, cosmetics, paint and felt-tip markers, as well as in health products such as antihistamines, cough drops and mouthwash.6 What’s more, all people have formaldehyde detectable in their blood as part of normal metabolism, and that level is approximately 10-fold higher than what any vaccine contains. Indeed, the quantity in vaccines is at least 600-fold lower than that necessary to induce toxicity in experimental animals.¹²

Aluminum is added to vaccines to boost and build a stronger immunity to the vaccine. But, not all vaccines contain aluminum, and again, those that do typically contain aluminum in amounts that are much less than what the average person consumes in a day from food, drinking water and medicines.⁶ Recently, the largest study ever was conducted on aluminum in vaccines. That study analyzed data on more than 1.2 million Danish children, examining whether cumulative aluminum exposure from vaccines was associated with 50 different conditions, including autism, ADHD, asthma and autoimmune disorders. The researchers found no association between aluminum exposure from vaccines and an increased risk for any of these conditions.¹²

Myth: Vaccines make people sick.

Fact: Vaccines help children avoid illness. Most vaccines are inactivated (killed) vaccines, so it is literally impossible to contract the disease from the vaccine.6 However, some kids do develop flu-like symptoms following vaccines, but these symptoms happen as children’s immune systems ramp up to produce antibodies focused on warding off disease.¹¹ If individuals are vaccinated with live vaccines, it may lead to a mild case of the disease. For example, the chickenpox vaccine can cause a child to develop a mild rash, which isn’t harmful, and can actually show the vaccine is working. An exception was the live oral polio vaccine, which could very rarely mutate and actually cause a case of polio. However, the oral polio vaccine is no longer administered in the U.S.⁶

Myth: Vaccines cause autism and sudden infant death syndrome (SIDS).

Fact: While diagnoses for autism and SIDS are usually made during the same time frame that childhood vaccines are administered, science has not yet determined the cause of them. The widespread fear that vaccines increase risk of autism stemmed from a 1997 study published in the journal The Lancet by Andrew Wakefield, a British surgeon, that suggested the measles, mumps, rubella (MMR) vaccine was increasing autism in British children. However, that study was completely discredited due to serious procedural errors, undisclosed financial conflicts of interest and ethical violations. And, after the article was retracted from the journal, Wakefield lost his medical license. Since the hypothesis was taken so seriously, other major studies were conducted, none of which found a link between any vaccine and the likelihood of developing autism.⁷

In 2014, based on the increasing prevalence of vaccine-preventable diseases due to the fear of a “link” between vaccinations and autism or autism spectrum disorder (ASD), researchers performed a meta-analysis to summarize the evidence from case-control and cohort studies that assessed the relationship between vaccine administration and the subsequent development of autism. Two reviewers extracted data on study characteristics, methods and outcomes, and disagreement was resolved by consensus with another author. In that meta-analysis, five cohort studies involving 1,256,407 children, and five case-control studies involving 9,920 children, the cohort data revealed no relationship between vaccination and autism or ASD, nor was there a relationship between autism and MMR, thimerosal or mercury (Hg). Similarly the case-control data found no evidence for increased risk of developing autism or ASD following MMR, Hg or thimerosal exposure when grouped by condition or exposure type.¹³

More recently, a World Health Organization (WHO) global expert committee on vaccine safety found, based on available evidence, no causal link exists between vaccines and ASD. The Nov. 27, 2025, analysis “focused first on the relationship between thimerosal-containing vaccines and ASD, and the association between vaccines in general and ASD. Evidence based on 31 primary research studies, published between January 2010 and August 2025, including data from multiple countries, strongly supports the positive safety profile of vaccines used during childhood and pregnancy, and confirms the absence of a causal link with ASD. The committee also assessed the review of potential health risks associated with vaccines with aluminum adjuvants, drawing on studies conducted from 1999 through March 2023. In addition, it reviewed a recent large cohort study analyzing nationwide registry data of children born in Denmark between 1997 and 2018. In summary, the available high-quality evidence shows no association between the trace amounts of aluminum used in some vaccines and ASD, supporting the ongoing use of vaccines with aluminum adjuvants.”¹⁴

There is also no evidence to support a link between vaccines and SIDS, the sudden and unexpected death of an apparently healthy baby younger than 12 months. In the last two decades, scientific understanding of SIDS has improved because medical experts realized a proportion of sudden deaths were caused by suffocation versus an unknown cause, which resulted in the term SIDS expanding to sudden unexpected infant death syndrome, or SUID. And, according to AAP, “numerous large-scale studies and research reviews, conducted over many years, have confirmed that vaccines do not cause SIDS.” In fact, the association says, the “incidence of SIDS is the same in children who do and do not receive vaccines, further supporting the fact that SIDS is not caused by vaccines.” What’s more, it says, “studies have shown that not only do vaccines not cause SIDS, they also may decrease the risk by 50 percent.” Research actually shows “SIDS is caused by something physiological, an abnormality in the anatomy such as a brain stem abnormality that prevents a baby from being able to wake up.”¹⁵

Myth: Vaccines haven’t been properly tested.

Fact: Vaccines are held to the highest scientific standards since they are administered to healthy people. According to AAP, all recommended childhood vaccines have undergone extensive research, including clinical trials that are tested on tens of thousands of study participants, and use placebos or comparison groups to ensure they are safe and effective. And, once approved, vaccines continue to be monitored for safety.¹⁶

Unfortunately, the myth that vaccines aren’t properly tested is perpetuated by a statement from U.S. Health and Human Services (HHS) Secretary Robert F. Kennedy, Jr. that was published in The New York Times on May 1, 2025. In that statement, Kennedy announced plans to require all new vaccines to be tested against placebos, which a spokesman for HHS called “a radical departure” from existing standards. However, most new vaccines are already tested either against placebos or, in some cases, against vaccines for other diseases.

According to an interview with John D. Gräbenstein, RPh, PhD, a pharmacist who has specialized in vaccines since 1983, with the Children’s Hospital of Philadelphia, “Before any vaccine can be widely used, we need to know if it is safe and if it provides any protective value (efficacy). This takes the form of Phase I, Phase II and Phase III studies. Testing vaccines against comparison products in Phase III studies has been the norm with vaccines licensed in the U.S., and around the world, for the last 75 years.” There are several valid options when choosing a placebo, says Dr. Gräbenstein: a saline (or salt) solution or a liquid that differs from the vaccine only in the antigenic content (the part that evokes a specific immune response). For example, he says, a candidate vaccine containing an adjuvant, a component that helps increase a protective immune response, may be compared to a solution that contains only the adjuvant. This option may be chosen if the adjuvant is known to cause injection-site side effects such as a sore arm.

Furthermore, Dr. Gräbenstein adds, while there are vaccine studies performed without using a placebo in the control arm of the study, those studies are “still robust, randomized, double-blinded studies, but the comparison may be a previously tested product to ensure the study is ethical.” The comparison product can be an alternate vaccine, an earlier or existing version of the vaccine, or the same vaccine delayed in time (for instance, after initial safety testing, an Ebola vaccine trial used a time-delayed vaccination group for comparison, because the researchers considered it unethical to have a group that did not receive potential protection against such a dangerous pathogen).¹⁷

Myth: The recommended vaccine schedule differs from other countries, so it must be incorrect.

Fact: It has been argued, especially most recently, that the U.S. childhood vaccine schedule should be modified to mirror recommendations from other developed nations. However, according to the organization Partnership to Fight Infectious Diseases, that argument “fundamentally misrepresents how vaccine schedules actually work — and why differences between countries exist in the first place.” This is because the U.S. operates under epidemiological and healthcare conditions vastly different from peer nations, especially in regard to disease burden, healthcare access and population demographics.

One major difference is that the U.S. healthcare system consists of a network of private insurance, Medicaid, Children’s Healthcare Insurance Program and safety-net programs that are distinctly different from the centralized, universal systems common in Europe. Also, comparisons to other countries lack context. For instance, critics of the U.S. childhood vaccination recommendation have recently compared ours to Denmark’s recommendation that calls for fewer doses of vaccines. But, as the Partnership to Fight Infectious Diseases points out, “a schedule developed for a small, wealthy nation with universal healthcare and low baseline disease prevalence reflects Denmark’s specific needs, not a universal standard.” And, it states even Denmark’s health authorities question the relevance of using their schedule as a model for other nations.

Moreover, comparing the U.S. recommendation to the United Kingdom, France, Germany, Israel, Japan and Scandinavian countries suggests the U.S. is not an outlier. They all vaccinate against approximately a dozen to 15 serious pathogens during childhood, but those countries base that on their own epidemiological realities. The U.S. schedule was calibrated over decades to American disease patterns and healthcare realities. “Public health decisions must be grounded in evidence and the realities of American healthcare delivery,” says the Partnership to Fight Infectious Diseases.¹⁸ 

Myth: Vaccines aren’t worth the risk.

Fact: Despite concerns, the U.S. has been successfully vaccinating children for decades without any credible studies linking vaccines to long-term health conditions.

According to a report that assessed and quantified the health benefits and economic impact of routine U.S. childhood immunizations among both Vaccines for Children (VFC)-eligible and non-VFC-eligible children, “Among approximately 117 million children born during 1994 to 2023, routine childhood vaccinations will have prevented approximately 508 million lifetime cases of illness, 32 million hospitalizations and 1,129,000 deaths, at a net savings of $540 billion in direct costs and $2.7 trillion in societal costs.… Childhood immunizations continue to provide substantial health and economic benefits, while promoting health equity.”¹⁹

Dispelling the Myths Now

In 2019, WHO named vaccine hesitancy one of the top 10 threats to global health. In a study titled “Vaccine Safety: Myths and Misinformation,” published in Frontiers in Microbiology, the authors write that one of the main factors behind vaccine hesitancy is lack of confidence in vaccine safety. Many parents fear adjuvants, preservatives, inactivating agents and manufacturing residuals, they state. And, they believe vaccines are causing autism, diabetes, developmental delays, hyperactivity and attention-deficit disorders, among others. 

Yet, vaccines are among the greatest public health achievements of modern times.²⁰ This is why healthcare workers, especially those in primary care, remain key influencers on vaccine decisions. It is important they communicate the facts and dispel the myths concerning childhood vaccines to parents so all children, even those who are unable to receive vaccines, are protected.

Estimated Illnesses and Hospitalizations Prevented by Childhood Vaccines in Children Born 1994-2023¹⁸